Chemistry Panchkula Set 1 2014-2015 Science (English Medium) Class 12 Question Paper Solution

Write a method by which lyophobic colloids can be coagulated.

What is the formula of a compound in which the element Y forms hcp lattice and atoms of X occupy 2/3^rd of tetrahedral voids?

Out of white phosphorus and red phosphorus, which one is more reactive and why?

Write the IUPAC name of the given compound:

Which would undergo S_N1 reaction faster in the following pair and why?

State Henry’s law.

Why do gases always tend to be less soluble in liquids as the temperature is raised?

State Raoult’s law for the solution containing volatile components

Write two differences between an ideal solution and a non-ideal solution.

Following reactions occur at cathode during the electrolysis of aqueous sodium chloride solution:

Na+(aq) + e⁻ ⟶ Na (s) E⁰ =  2.71 V

H+(aq) + e⁻ ⟶ `1/2`  H₂ (g) E⁰ = 0.00 V

On the basis of their standard reduction electrode potential (E⁰) values, which reaction is feasible at the cathode and why?

Why does the cell potential of mercury cell remain constant throughout its life?

Why do the transition elements have higher enthalpies of atomisation?

In 3d series (Sc to Zn), which element has the lowest enthalpy of atomisation and why?

Write down the IUPAC name of the following complex: [Co(NH₃)₅ (NO₂)](NO₃)₂

Using IUPAC norms, write the formula for the following: 

Potassium tetracyanidonickelate(II)

Name the reagents used in the following reactions:

Name the reagents used in the following reactions:

Calculate the amount of CaCl₂ (molar mass = 111 g mol⁻¹) which must be added to 500 g of water to lower its freezing point by 2 K, assuming CaCl₂ is completely dissociated. (K_f for water = 1.86 K kg mol⁻¹)

An element with density 10 g cm⁻³ forms a cubic unit cell with edge length of 3 × 10⁻⁸ cm. What is the nature of the cubic unit cell if the atomic mass of the element is 81 g mol⁻¹?

Calculate emf of the following cell at 25°C:

\[\ce{Sn/Sn^2+ (0.001 M) || H+ (0.01 M) | H2_{(g)} (1 bar) | Pt_{(s)}}\]

Given: \[\ce{E^\circ(Sn^2+/sn) = -0.14 V, E^\circ H+/H2 = 0.00 V (log 10 = 1)}\]

Give reasons for the following observations:

Physisorption decreases with increase in temperature.

Give reasons for the following observations: Addition of alum purifies the water

Give reasons for the following observations:

Brownian movement provides stability to the colloidal solution.

Name the method used for the refining of zirconium.

What is the role of CO in the extraction of Iron?

Reduction of metal oxide to metal becomes easier if the metal obtained is in liquid state. Why?

How would you account for the following:

The chemistry of actinoids is more complicated as compared to lanthanoids.

How would you account for the following: Transition metals form complex compounds.

Complete the following equation:

\[\ce{2MnO4- + 6H+ + 5NO2- ->}\]

Draw the geometrical isomers of complex \[\ce{[Co(en)2Cl2]+}\].

On the basis of crystal field theory, write the electronic configuration for d⁴ ion if Δ₀ > P.

[NiCl₄]²⁻ is paramagnetic, while [Ni(CO)₄] is diamagnetic, though both are tetrahedral. Why? (Atomic number of Ni = 28)

How do you convert the following: Prop-1-ene to 1-fluoropropane

How do you convert the following: Chlorobenzene to 2-chlorotoluene

How do you convert the following:

Ethanol to propanenitrile

Write the main products when n-butyl chloride is treated with alcoholic KOH.

Write the main products when

2, 4, 6-trinitrochlorobenzene is subjected to hydrolysis

Write the main products when methyl chloride is treated with AgCN.

Give reasons for the following:

o-nitrophenol is more acidic than o-methoxyphenol.

Give reasons for the following: Butan-1-ol has a higher boiling point than diethyl ether.

 Give reasons for the following:

(CH₃)₃C–O–CH₃ on reaction with HI gives (CH₃)₃C–I and CH₃–OH as the main products and not (CH₃)₃C–OH and CH₃–I.

Predict the products of the following reactions:

Predict the products of the following reactions:

Predict the products of the following reactions:

Write the names and structures of the monomers of the following polymers: Nylon-6

Write the names and structures of the monomers of the following polymers: Novolac

Write the names and structures of the monomers of the following polymers: Buna-N

Which one of the following is a polysaccharide:

Starch, Maltose, Fructose, Glucose

What is the difference between native protein and denatured protein?

Write the name of the vitamin responsible for the coagulation of blood.

Seeing the growing cases of diabetes and depression among young children, Mr Lugani, the principal of one reputed school, organised a seminar in which he invites parents and principals. They all resolved this issue by strictly banning junk food in schools and introducing healthy snacks and drinks like soup, lassi, milk etc. in school canteens. They also decided to make compulsory half an hour of daily physical activities for the students in the health survey in most of the school and discovered a tremendous improvement in the health of the students

After reading the above passage, answer the following questions:

(i) What are the values (at least two) displayed by Mr Lugani?

(ii) As a student, how can you spread awareness about this issue?

(iii) What are antidepressant drugs? Give an example.

(iv) Name the sweetening agent used in the preparation of sweets for a diabetic patient.

Write the chemical equation involved in the following reaction:

Hoffmann-bromamide degradation reaction

Illustrate the following reaction giving suitable example in each case: Diazotisation

Illustrate the following reaction giving suitable example in each case:Gabriel phthalimide synthesis

Distinguish between the following pairs of compounds: Aniline and N-methylaniline

Write the structures of main products when benzene diazonium chloride `(C_6H_5N_2^(+)Cl^-)`reacts with the following reagents:

CuCN/KCN

Write the structures of main products when benzene diazonium chloride `(C_6H_5N_2^(+)Cl^-)`reacts with the following reagents:

H₂O

Write the structures of main products when benzene diazonium chloride `(C_6H_5N_2^(+)Cl^-)`reacts with the following reagents:

CH₃CH₂OH

Arrange the following:

Aniline, p-nitroaniline, p-methylaniline - in the increasing order of their basic strength

What is rate of reaction?

Write two factors that affect the rate of reaction.

The rate constant of a first order reaction increases from 4 × 10⁻² to 8 × 10⁻² when the temperature changes from 27°C to 37°C. Calculate the energy of activation (Ea). (log 2 = 0.301, log 3 = 0.4771, log 4 = 0.6021)

For a reaction A + B ⟶ P, the rate is given by

Rate = k [A] [B]²

How is the rate of reaction affected if the concentration of B is doubled?

For a reaction A + B ⟶ P, the rate is given by

Rate = k [A] [B]²

What is the overall order of reaction if A is present in large excess?

A first order reaction takes 23.1 minutes for 50% completion. Calculate the time required for 75% completion of this reaction.

(log 2 = 0.301, log 3 = 0.4771, log 4 = 0.6021)

Account for the following: Interhalogens are more reactive than pure halogens.

Account for the following:

N₂ is less reactive at room temperature.

Account for the following: Reducing character increases from NH₃ to BiH₃.

Draw the structures of the following: H₄P₂O₇ (Pyrophosphoric acid)

Draw the structures of the following molecules: XeF₄

which poisonous gas is evolved when white phosphorus is heated with conc. NaOH solution? Write the chemical equation involved.

Which noble gas has the lowest boiling point?

Fluorine is a stronger oxidising agent than chlorine. Why?

What happens when 

H₃PO₃ is heated ?

Write the reactions involved.

Complete the equation

PbS + O₃ ⟶